Note: Descriptions are shown in the official language in which they were submitted.
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A POLYETHYLENE BLEND COMPOSITION AND
FILM MADE THEREFROM
Field of Invention
The instant invention relates to a polyethylene blend composition and film
made
therefrom.
Background of the Invention
For collation shrink film and biaxially oriented polyethylene (BOPE) shrink
film, a
number of film properties are needed to obtain adequate package performance,
including high
shrink force/tension, good optics (low haze and high gloss), low elongation,
and good
dart/puncture performance. Currently structures typically utilize >50-60% low
density
polyethylene (LDPE) for the majority of these properties in either a monolayer
or 3 layer
structure. The addition of LDPE generally results in a reduction in especially
toughness
properties such as dart and puncture. Therefore, there remains a need for a
polyethylene
composition which provides these various properties.
Summary of the Invention
The instant invention provides a polyethylene blend composition and film made
therefrom.
In one embodiment, the instant invention provides a polyethylene blend
composition
comprising from 10 to 100 percent by weight of an ethylene-based polymer made
by the
process of: selecting an ethylene/a-olefin interpolymer (LLDPE) having a
Comonomer
Distribution Constant (CDC) in the range of from 75 to 300, a vinyl
unsaturation of less than
150 vinyls per one million carbon atoms of the ethylene/a-olefin interpolymer;
a zero shear
viscosity ratio (ZSVR) in the range from 4 to 50; a density in the range of
from 0.925 to
0.950 g/cm3, a melt index (12) in a range of from 0.1 to 2.5 g/ 10 minutes, a
molecular weight
distribution (Mw/Mn) in the range of from 1.8 to 4.0; reacting said ethylene/a-
olefin
interpolymer with an alkoxy amine derivative in an amount equal to or less
than 900 parts
derivative per million parts by weight of total ethylene/a-olefin interpolymer
under
conditions sufficient to increase the melt strength of the ethylene/a-olefin
interpolymer; and
optionally from 5 to 90 percent by weight of a low density polyethylene
composition;
wherein when said polyethylene blend composition is formed into a film via a
blown film
process.
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BRIEF DESCRIPTION OF THE DRAWINGS
For the purpose of illustrating the invention, there is shown in the drawings
a form
that is exemplary; it being understood, however, that this invention is not
limited to the
precise arrangements and illustrations shown.
Fig. 1 is a graph illustrating the dynamical mechanical spectroscopy complex
viscosity data at 190 C versus frequency for Inventive Example 1 and
Comparative Example
1;
Fig. 2 is a graph illustrating dynamical mechanical spectroscopy tan delta
data at 190
C versus frequency for Inventive Example 1 and Comparative Example 1;
Fig. 3 is a graph illustrating dynamical mechanical spectroscopy data of phase
angle
vs. complex modulus (Van-Gurp Palmen plot) at 190 C for Inventive Example 1
and
Comparative Example 1;
Fig. 4 is a graph illustrating melt strength data at 190 C vs. velocity of
Inventive
Example 1 and Comparative Example 1;
Fig. 5 is a graph illustrating a Conventional GPC plot for Inventive Example 1
and
Comparative Example 1;
Fig. 6 illustrates the CEF plot for Inventive Example 1 and Comparative
Example 1;
and
Fig. 7 illustrates the MW Ratio plot for Inventive Example 1 and Comparative
Example 1.
Detailed Description of the Invention
The instant invention provides a polyethylene blend composition and film made
therefrom.
The term "composition," as used, includes a mixture of materials which
comprise the
composition, as well as reaction products and decomposition products formed
from the
materials of the composition.
The terms "blend" or "polymer blend," as used herein, refers to an intimate
physical
mixture (that is, without reaction) of two or more polymers. A blend may or
may not be
miscible (not phase separated at molecular level). A blend may or may not be
phase
separated. A blend may or may not contain one or more domain configurations,
as
determined from transmission electron spectroscopy, light scattering, x-ray
scattering, and
other methods known in the art. The blend may be affected by physically mixing
the two or
more polymers on the macro level (for example, melt blending resins or
compounding) or the
micro level (for example, simultaneous forming within the same reactor).
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The term "linear" as used herein refers to polymers where the polymer backbone
of
the polymer lacks measurable or demonstrable long chain branches, for example,
the polymer
can be substituted with an average of less than 0.01 long branches per 1000
carbons.
The term "polymer" as used herein refers to a polymeric compound prepared by
polymerizing monomers, whether of the same or a different type. The generic
term polymer
thus embraces the term "homopolymer," usually employed to refer to polymers
prepared from
only one type of monomer, and the term "interpolymer" as defined below. The
terms
"ethylene/cc-olefin polymer" is indicative of interpolymers as described.
The term "interpolymer" as used herein, refers to polymers prepared by the
polymerization of at least two different types of monomers. The generic term
interpolymer
includes copolymers, usually employed to refer to polymers prepared from two
different
monomers, and polymers prepared from more than two different types of
monomers.
The term "ethylene-based polymer" refers to a polymer that contains more than
50
mole percent polymerized ethylene monomer (based on the total amount of
polymerizable
monomers) and, optionally, may contain at least one comonomer.
The term "ethylene/cc-olefin interpolymer" refers to an interpolymer that
contains
more than 50 mole percent polymerized ethylene monomer (based on the total
amount of
polymerizable monomers) and at least one a-olefin.
In a first embodiment, the instant invention provides a polyethylene blend
composition comprising from 10 to 100 percent by weight of an ethylene-based
polymer
made by the process of: selecting an ethylene/a-olefin interpolymer having a
Comonomer
Distribution Constant (CDC) in the range of from 75 to 300, a vinyl
unsaturation of less than
150 vinyls per one million carbon atoms of the ethylene/a-olefin interpolymer;
a zero shear
viscosity ratio (ZSVR) in the range from 4 to 50; a density in the range of
from 0.925 to
0.950 g/cm3, a melt index (I2) in a range of from 0.1 to 2.5 g/ 10 minutes, a
molecular weight
distribution (Mw/M.) in the range of from 1.8 to 4; reacting said ethylene/a-
olefin
interpolymer with an alkoxy amine derivative in an amount equal to or less
than 900 parts
derivative per million parts by weight of total ethylene/a-olefin interpolymer
under
conditions sufficient to increase the melt strength of the ethylene/a-olefin
interpolymer; and
optionally from 5 to 90 percent by weight of a low density polyethylene
composition;
wherein when said polyethylene blend composition is formed into a film.
The polyethylene blend composition comprises from 10 to 100 percent by weight
of
an ethylene-based polymer. All individual values and subranges from 10 to 100
percent by
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weight are included herein and disclosed herein; for example, the amount of
ethylene-based
polymer in the polyethylene blend composition may range from a lower limit of
10, 20, 30,
40, 50, 60, 70, 80 or 90 percent by weight to an upper limit of 15, 25, 35,
45, 55, 65, 75, 85,
95 or 100 percent by weight. For example, the amount of ethylene-based polymer
can be
from 10 to 100 percent by weight, or in the alternative, the amount of
ethylene-based polymer
can be from 10 to 60 percent by weight, or in the alternative, the amount of
ethylene-based
polymer can be from 60 to 100 percent by weight, or in the alternative, the
amount of
ethylene-based polymer can be from 20 to 80 percent by weight, or in the
alternative, the
amount of ethylene-based polymer can be from 30 to 50 percent by weight.
The ethylene-based polymer is produced by selecting an ethylene/a-olefin
interpolymer having a Comonomer Distribution Constant (CDC) in the range of
from 75 to
300, a vinyl unsaturation of less than 150 vinyls per one million carbon atoms
of the
ethylene/a-olefin interpolymer; a zero shear viscosity ratio (ZSVR) from 4 to
50; a density in
the range of from 0.925 to 0.950 g/cm3, a melt index (I2) in a range of from
0.1 to 2.5 g/ 10
minutes, a molecular weight distribution (Mw/Mi,) in the range of from 1.8 to
4.
All individual values and subranges of CDC from 75 to 300 are included herein
and
disclosed herein; for example, the CDC of the ethylene/a-olefin interpolymer
can be from a
lower limit of 75, 125, 175, 225 or 275 to an upper limit of 100, 150, 200,
250 or 300. For
example, the CDC of the ethylene/a-olefin interpolymer can be from 75 to 175,
or in the
alternative, the CDC of the ethylene/a-olefin interpolymer can be from 135 to
300, or in the
alternative, the CDC of the ethylene/a-olefin interpolymer can be from 75 to
175, or in the
alternative, the CDC of the ethylene/a-olefin interpolymer can be from 100 to
175, or in the
alternative, the CDC of the ethylene/a-olefin interpolymer can be from 125 to
200.
All individual values and subranges of a vinyl unsaturation of less than 150
vinyls per
one million carbon atoms of the ethylene/a-olefin interpolymer are included
herein and
disclosed herein; for example, the vinyl unsaturation can be from an upper
limit of 150 vinyls
per one million carbon atoms of the ethylene/a-olefin interpolymer, or in the
alternative, the
vinyl unsaturation can be from an upper limit of 125 vinyls per one million
carbon atoms of
the ethylene/a-olefin interpolymer, or in the alternative, the vinyl
unsaturation can be from an
upper limit of 100 vinyls per one million carbon atoms of the ethylene/a-
olefin interpolymer,
or in the alternative, the vinyl unsaturation can be from an upper limit of 50
vinyls per one
million carbon atoms of the ethylene/a-olefin interpolymer.
All individual values and subranges of a zero shear viscosity ratio (ZSVR)
from 4 to
50 are included herein and disclosed herein; for example, the ZSVR of the
ethylene/a-olefin
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interpolymer can be from a lower limit of 4, 10, 16, 20, 26 or 29 to an upper
limit of 5, 11,
17, 24, 28, 30, 35, 40, 45, or 50. For example, the ZSVR of the ethylene/a-
olefin
interpolymer can be from 4 to 50, or in the alternative, the ZSVR of the
ethylene/a-olefin
interpolymer can be from 4 to 30, or in the alternative, the ZSVR of the
ethylene/a-olefin
interpolymer can be from 16 to 30, or in the alternative, the ZSVR of the
ethylene/a-olefin
interpolymer can be from 8 to 30.
All individual values and subranges of a density from 0.925 to 0.950 g/cm3 are
included herein and disclosed herein; for example, the density of the
ethylene/a-olefin
interpolymer can be from a lower limit of 0.925, 0.935, or 0.945 g/cm3 to an
upper limit of
0.93, 0.94, or 0.950 g/cm3. For example, the density of the ethylene/a-olefin
interpolymer
can be from 0.925 to 0.950 g/cm3, or in the alternative, the density of the
ethylene/a-olefin
interpolymer can be from 0.930 to 0.950 g/cm3, or in the alternative, the
density of the
ethylene/a-olefin interpolymer can be from 0.925 to 0.94 g/cm3, or in the
alternative, the
density of the ethylene/a-olefin interpolymer can be from 0.93 to 0.945 g/cm3.
All individual values and subranges of a melt index (12) from 0.1 to 2.5 g/ 10
minutes
are included herein and disclosed herein; for example, the melt index can be
from a lower
limit of 0.1, 0.2, 0.3, 0.5, 1, 1.5 or 2 g/10 minutes to an upper limit of
0.3, 0.5, 0.8, 1.3, 1.8,
2.3 or 2.5 g/10 minutes. For example, the melt index of the ethylene/a-olefin
interpolymer
can be from 0.1 to 2.5 g/10 minutes, or in the alternative, the melt index of
the ethylene/a-
olefin interpolymer can be from 0.1 to 1.25 g/10 minutes, or in the
alternative, the melt index
of the ethylene/a-olefin interpolymer can be from 1.25 to 2.5 g/10 minutes, or
in the
alternative, the melt index of the ethylene/a-olefin interpolymer can be from
0.5 to 2 g/10
minutes, or in the alternative, the melt index of the ethylene/a-olefin
interpolymer can be
from 1 to 2 g/10 minutes, or in the alternative, the melt index of the
ethylene/a-olefin
interpolymer can be from 0.8 to 1.5 g/10 minutes, or in the alternative, the
melt index of the
ethylene/a-olefin interpolymer can be from 0.6 to 1 g/10 minutes, or in the
alternative, the
melt index of the ethylene/a-olefin interpolymer can be from 0.1 to 0.5 g/10
minutes.
All individual values and subranges of a molecular weight distribution
(Mw/Mi,) from
1.8 to 4 are included herein and disclosed herein; for example, the molecular
weight
distribution of the ethylene/a-olefin interpolymer can be from a lower limit
of 1.8, 2.4, 2.7,
3.0 or 3.6 to an upper limit of 2, 2.6, 3.2, 3.4, 3.8 or 4. For example, the
molecular weight
distribution of the ethylene/a-olefin interpolymer can be from 1.8 to 4, or in
the alternative,
the molecular weight distribution of the ethylene/a-olefin interpolymer can be
from 1.8 to
2.5, or in the alternative, the molecular weight distribution of the
ethylene/a-olefin
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interpolymer can be from 2.5 to 4, or in the alternative, the molecular weight
distribution of
the ethylene/a-olefin interpolymer can be from 2.2 to 3.4, or in the
alternative, the molecular
weight distribution of the ethylene/a-olefin interpolymer can be from 2 to 3.
The polymeric composition optionally comprises from 500 to 2000 ppm secondary
antioxidant based on the total polymeric composition weight. Secondary
antioxidants prevent
formation of additional free radicals by decomposing the peroxide into
thermally stable, non-
radical, non-reactive products by means of an efficient alternative to
thermolysis and
generation of free radicals. Phosphites and thioesters are examples of
functionalities
operating as secondary antioxidants. All individual values and subranges from
500 to 2000
ppm are included herein and disclosed herein; for example, the amount of
secondary
antioxidant can be from a lower limit of 500, 700, 900, 1100, 1300, 1500, 1700
or 1900 ppm
to an upper limit of 600, 800, 1000, 1200, 1400, 1600, 1800 or 2000 ppm. For
example,
when present, the secondary antioxidant may be present in an amount from 500
to 2000 ppm,
or in the alternative, the secondary antioxidant may be present in an amount
from 1250 to
2000 ppm, or in the alternative, the secondary antioxidant may be present in
an amount from
500 to 1250 ppm, or in the alternative, the secondary antioxidant may be
present in an
amount from 750 to 1500 ppm. An example of a secondary antioxidant is IRGAFOS
168 or
tris(2,4-ditert-butylphenyl)phosphite, which is commercially available from
BASF.
In one embodiment, the secondary antioxidant is present in the polyethylene
resin
prior to mixing with the masterbatch. In an alternative embodiment, the
secondary
antioxidant is a component in the masterbatch.
The ethylene-based polymer is produced by reacting the ethylene/a-olefin
interpolymer with an alkoxy amine derivative in an amount from greater than 0
to equal to or
less than 900 parts alkoxy amine derivative per million (ppm) parts by weight
of total
ethylene/a-olefin interpolymer under conditions sufficient to increase the
melt strength and/or
increase the extensional viscosity of the ethylene/a-olefin interpolymer. All
individual values
and subranges from greater than 0 to 900 parts alkoxy amine derivative per
million parts by
weight of total ethylene/a-olefin interpolymer are included herein and
disclosed herein. For
example, the amount of alkoxy amine derivative can be from a lower limit of
0.5, 1, 15, 50,
100, 200, 300, 400, 500, 600, 700, or 800 ppm to an upper limit of 900, 850,
750, 650, 550,
450, 350, 250, 150, 60, 20 or 5 ppm. For example, the amount of the alkoxy
amine derivative
can be from greater than 0 to 900 ppm, or in the alternative, the amount of
the alkoxy amine
derivative can be from 1 to 900 ppm, or in the alternative, the amount of the
alkoxy amine
derivative can be from 15 to 600 ppm, or in the alternative, the amount of the
alkoxy amine
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derivative can be from 25 to 400 ppm, or in the alternative, the amount of the
alkoxy amine
derivative can be from 30 to 200 ppm, or in the alternative, the amount of the
alkoxy amine
derivative can be from 15 to 70 ppm.
For purposes of the present invention "alkoxy amine derivatives" includes
nitroxide
derivatives. The alkoxy amine derivatives correspond to the formula:
(R1)(R2)N¨O¨R3
where Riand R2 are each independently of one another, hydrogen, C4-C42 alkyl
or C4-C42 aryl
or substituted hydrocarbon groups comprising 0 and/or N, and where R1 and R2
may form a
ring structure together; and where R3 is hydrogen, a hydrocarbon or a
substituted
hydrocarbon group comprising 0 and/or N. In particular aspects of the
invention, groups for
R3 include --C1-C19 alkyl; --C6-Cio aryl; --C2-C19 akenyl; ¨0¨Ci-C19 alkyl;
¨0¨ C6-CE0
aryl; --NH¨C1-C19 alkyl; --NH-- C6-Cio aryl; --N--(Ci-C19 alky1)2. In a
particular aspect of
the invention, R3 contains an acyl group. The alkoxy amine derivative may form
nitroxylradical (R1)(R2)N-0* or amynilradical (R1)(R2)N* after decomposition
or
thermolysis.
A particularly preferred species of alkoxy amine derivative is 9-(acetyloxy)-
3,8,10-
triethy1-7,8,10-trimethy1-1,5-dioxa-9-azaspiro[5.5]u- ndec-3-yl]methyl
octadecanoate which
has the following chemical structure:
a NIR lit
II Mi:
Mt ¨ CCR.:)16.`w.C.w.q.l.w3(.2 ======0
N-041/4
Me
Examples of some preferred species for use in the present invention include
the
following:
3X)
\
A
\
/---
`k\ 1
I
fl=
__ --
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In general hydroxyl amine esters are more preferred with one particularly
favored
hydroxyl amine ester being 9-(acetyloxy)-3,8,10-triethy1-7,8,10-trimethy1-1,5-
dioxa-9-
azaspiro[5.5]u- ndec-3-yl]methyl octadecanoate.
Conditions sufficient to increase the melt strength of the ethylene/a-olefin
interpolymer are described in detail in U.S. Application No. 13/515832, the
disclosure of
which is incorporated herein by reference.
The ethylene-based polymer has a melt strength from 2 to 20 cN. All individual
values and subranges of a melt strength from 2 to 20 cN are included herein
and disclosed
herein; for example, the melt strength of the ethylene-based polymer can be
from a lower
limit of 2, 4, 6, 8, 10, 12, 14, 16, or 18 cN to an upper limit of 3, 5, 7, 9,
11, 13, 15, 17, 19 or
20 cN. For example, the melt strength of the ethylene-based polymer can be
from 2 to 20 cN,
or in the alternative, the melt strength of the ethylene-based polymer can be
from 4 to 12 cN,
or in the alternative, the melt strength of the ethylene-based polymer can be
from 10 to 20
cN, or in the alternative, the melt strength of the ethylene-based polymer can
be from 8 to 16
cN, or in the alternative, the melt strength of the ethylene-based polymer can
be from 10 to
15 cN.
The polyethylene blend composition comprises optionally from 5 to 90 percent
by
weight of a low density polyethylene (LDPE) composition. All individual values
and
subranges from 5 to 90 percent by weight are included herein and disclosed
herein; for
example, when present, the LDPE can be present in an amount from a lower limit
of 5, 20,
45, 60, 75 or 80 percent by weight to an upper limit of 10, 20, 40, 70 or 90
percent by weight.
For example, the amount of LDPE in the polyethylene blend composition, when
present, may
be an amount from 5 to 90 percent by weight, or in the alternative, from 5 to
60 percent by
weight, or in the alternative, from 50 to 90 percent by weight, or in the
alternative, from 20 to
80 percent by weight, or in the alternative, from 30 to 70 percent by weight.
Low density polyethylene useful in the polyethylene blend composition may have
a
density in the range of from 0.910 g/cm3 to 0.940 g/cm3. All individual values
and subranges
from 0.910 g/cm3 to 0.940 g/cm3 are included herein and disclosed herein; for
example, the
LDPE can have a density from a lower limit of 0.910, 0.915, 0.92, 0.925, 0.93,
or 0.935
g/cm3 to an upper limit of 0.913, 0.918, 0.923, 0.928, 0.933, 0.939, or 0.940
g/cm3. For
example, the density of the LDPE can be from 0.910 g/cm3 to 0.940 g/cm3, or in
the
alternative, from 0.915 g/cm3 to 0.935 g/cm3, or in the alternative, from 0.91
g/cm3 to 0.925
g/cm3. The LDPE may have a melt index (I2) from 0.1 to 5 g/10 minutes. All
individual
values and subranges from 0.1 to 5 g/10 minutes are included herein and
disclosed herein; for
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example, the melt index of the LDPE can be from a lower limit of 0.1, 1, 2, 3,
or 4 g/10
minutes to an upper limit of 0.5, 1.5, 2.5, 3.5, 4.5 or 5 g/10 minutes. For
example, the melt
index of the LDPE can be from 0.1 to 5 g/10 minutes, or in the alternative,
the melt index of
the LDPE can be from 0.2 to 2 g/10 minutes, or in the alternative, the melt
index of the LDPE
can be from 0.1 to 2.5 g/10 minutes, or in the alternative, the melt index of
the LDPE can be
from 2.4 to 5 g/10 minutes, or in the alternative, the melt index of the LDPE
can be from 0.5
to 3 g/10 minutes.
In another embodiment, a film formed via a blown film process from the
polyethylene
blend composition and having a thickness of approximately 2 mil has an MD
shrink tension
of greater than 16 psi. All individual values and subranges of MD shrink
tension of greater
than 16 psi are included herein and disclosed herein; for example, the MD
shrink tension can
be from a lower limit of 16, 16.2, 16.4, 16.6, 16.8, or 17 psi. In one
embodiment, the MD
shrink tension has an upper limit of 50 psi. All individual values and
subranges from less
than or equal to 50 psi are included herein and disclosed herein; for example,
the upper limit
of the MD shrink tension can be 50, 40, 30, or 20 psi.
In another embodiment, a film formed via a blown film process from the
polyethylene
blend composition and having a thickness of approximately 2 mil has a CD
shrink tension of
greater than or equal to 1 psi. All individual values and subranges of CD
shrink tension of
greater than or equal to 1 psi are included herein and disclosed herein; for
example, the CD
shrink tension can be from a lower limit of 1, 1.005, 1.01, 1.015, 1.02, 1025
or 1.03 psi. In
one embodiment, the CD shrink tension has an upper limit of 10 psi. All
individual values
and subranges from less than or equal to 10 psi are included herein and
disclosed herein; for
example, the upper limit of the CD shrink tension can be 10, 8, 6, 4, or 2
psi.
In yet another embodiment, the ethylene-based polymer is produced by reacting
the
ethylene/a-olefin interpolymer with from 10 ppm to 1000 ppm of at least one
peroxide
having a 1 hour half-life decomposition temperature from 160 C to 250 C
under
conditions sufficient to increase the melt strength and/or increase the
extensional viscosity of
the ethylene/a-olefin interpolymer. One example of such a peroxide is TRIGONOX
311,
which is commercially available from AkzoNobel Polymer Chemicals LLC (Chicago,
IL,
USA).
The polyethylene blend composition may be used for any appropriate end use.
The
inventive polyethylene blend composition may be employed in a variety of
conventional
thermoplastic fabrication processes to produce useful articles, including
objects comprising at
least one film layer, such as a monolayer film, or at least one layer in a
multilayer film
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prepared by cast, blown, calendered, or extrusion coating processes; molded
articles, such as
blow molded, injection molded, or rotomolded articles; extrusions; fibers; and
woven or non-
woven fabrics.
The inventive polyethylene blend composition may further be blended with other
natural or synthetic materials, polymers, additives, reinforcing agents,
ignition resistant
additives, antioxidants, stabilizers, colorants, extenders, crosslinkers,
blowing agents, and
plasticizers. Suitable polymers for blending with the inventive polyethylene
blend
composition are described in PCT Publication W02011/159376, the entire
disclosure of
which is incorporated herein in by reference.
In another embodiment, the invention provides a film comprising the
polyethylene
blend composition according to any of the embodiments disclosed herein.
Examples
The following examples illustrate the present invention but are not intended
to limit
the scope of the invention.
Resin Production
All (co)monomer feeds (ethylene, 1-octene) and the process solvent (a narrow
boiling
range high-purity isoparaffinic solvent trademarked Isopar E and commercially
available
from Exxon Mobil Corporation) are purified with molecular sieves before
introduction into
the reaction environment. High purity hydrogen is supplied by cylinders and is
ready for
metering and delivery to the reactors and it is not further purified. The
reactor monomer feed
(ethylene) streams are pressurized via mechanical compressor to above reaction
pressure at
725 psig. The solvent feeds are mechanically pressurized to above reaction
pressure at 725
psig. The comonomer (1-octene) feed is also mechanically pressurized and
injected directly
into the feed stream for the second reactor. Three catalyst components are
injected into the
first reactor (CAT-A, RIBS-2, and MMAO-3A). Prior to injection in the reactor
all of these
catalyst components are batch diluted with Isopar E to an appropriate
concentration to allow
metering within the plant capability. The catalyst components to the second
reactor are
similarly delivered with three components fed to the second reactor (CAT-A,
RIBS-2, and
MMAO-3A). These catalyst components are also batch diluted with Isopar E to an
appropriate concentration to allow metering within the plant capability. All
catalyst
components are independently mechanically pressurized to above reaction
pressure at 725
psig. All reactor catalyst feed flows are measured with mass flow meters and
independently
controlled with positive displacement metering pumps.
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The continuous solution polymerization reactors consist of two liquid full,
non-
adiabatic, isothermal, circulating, and independently controlled loops
operating in a series
configuration. Each reactor has independent control of all solvent, monomer,
comonomer,
hydrogen, and catalyst component feeds. The combined solvent, monomer,
comonomer and
hydrogen feed to each reactor is independently temperature controlled to
anywhere between
C to 50 C and typically 50 C for the first reactor and 30 C for the second
reactor by
passing the feed stream through one or more heat exchangers. The fresh
comonomer feed to
the polymerization reactor is aligned to the second reactor. The total fresh
feed to each
polymerization reactor is injected into the reactor at two locations per
reactor roughly with
equal reactor volumes between each injection location. The fresh feed to both
reactors is
controlled typically with each injector receiving half of the total fresh feed
mass flow. The
polymerization reaction contents exiting the first reactor are injected into
the second reactor
near the lower pressure fresh feed. The catalyst components for the first
reactor are injected
into the polymerization reactor through specially designed injection stingers
and are each
injected into the same relative location in the first reactor. The catalyst
components for the
second reactor are injected into the second polymerization reactor through
specially designed
injection stingers and are each injected into the same relative location in
the second reactor.
The primary catalyst component feed for each reactor (CAT-A) is computer
controlled to maintain the individual reactor monomer concentration at a
specified target.
The cocatalyst components (RIBS-2 and MMAO-3A) are fed based on calculated
specified
molar ratios to the primary catalyst component. Immediately following each
fresh injection
location (either feed or catalyst), the feed streams are mixed with the
circulating
polymerization reactor contents with Kenics static mixing elements. The
contents of each
reactor are continuously circulated through heat exchangers responsible for
removing much
of the heat of reaction and with the temperature of the coolant side
responsible for
maintaining an isothermal reaction environment at the specified reactor
temperature.
Circulation around each reactor loop is provided by a screw pump. The effluent
from the
first polymerization reactor (containing solvent, monomer, comonomer,
hydrogen, catalyst
components, and dissolved polymer) exits the first reactor loop and passes
through a control
valve (responsible for controlling the pressure of the first reactor at a
specified target) and is
injected into the second polymerization reactor of similar design. After the
combined
polymerization stream exits the second reactor it is contacted with water to
stop the reaction.
The stream then goes through another set of Kenics static mixing elements to
evenly disperse
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the water catalyst kill and any additives if used. No additives or
antioxidants were added in
this case.
The effluent (containing solvent, monomer, comonomer, hydrogen, catalyst
components, and dissolved polymer) then passes through a heat exchanger to
raise the stream
temperature in preparation for separation of the polymer from the lower
boiling reaction
components. The stream then enters a two stage separation and devolatization
system where
the polymer is removed from the solvent, hydrogen, and non-reacted monomer and
comonomer. The recycled stream is purified before entering the reactor again.
The polymer
stream then enters a die specially designed for underwater pelletization, is
cut into uniform
solid pellets, dried, and transferred into a hopper.
The non-polymer portions removed in the devolatilization step pass through
various
pieces of equipment which separate most of the monomer which is removed from
the system
and sent to a flare for destruction. Most of the solvent and comonomer are
recycled back to
the reactor after passing through purification beds. This solvent can still
have non-reacted
co-monomer in it that is fortified with fresh co-monomer prior to re-entry to
the reactor as
previously discussed. This fortification of the co-monomer is an essential
part of the product
density control method. This recycle solvent can contain some dissolved
hydrogen which is
then fortified with fresh hydrogen to achieve the polymer molecular weight
target. A very
small amount of solvent leaves the system where it is purged from the system.
Tables 1-4 summarize the conditions for polymerization for the starting
ethylene/a-
olefin interpolymer, or base resin. The untreated base resin is used as
Comparative Example
1 and was subsequently treated to produce Inventive Example 1.
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Table 1: Process reactor feeds used to make base resin.
REACTOR FEEDS CE 1
Primary Reactor Feed Temperature ( C) 50
Primary Reactor Total Solvent Flow (lb/hr) 892
Primary Reactor Fresh Ethylene Flow (lb/hr) 170
Primary Reactor Total Ethylene Flow (lb/hr) 177
Comonomer Type 1-octene
Primary Reactor Fresh Comonomer Flow (lb/hr) 0
Primary Reactor Total Comonomer Flow (lb/hr) 12.8
Primary Reactor Fresh Hydrogen Flow (sccm) 2,388
Secondary Reactor Feed Temperature ( C) 30
Secondary Reactor Total Solvent Flow (lb/hr) 480
Secondary Reactor Fresh Ethylene Flow (lb/hr) 180
Secondary Reactor Total Ethylene Flow (lb/hr) 184
Secondary Reactor Fresh Comonomer Flow (lb/hr) 8.2
Secondary Reactor Total Comonomer Flow (lb/hr) 15
Secondary Reactor Fresh Hydrogen Flow (sccm) 10,152
Table 2: Process reaction conditions used to make base resin.
REACTION CE 1
Primary Reactor Control Temperature ( C) 185
Primary Reactor Pressure (Psig) 725
Primary Reactor Ethylene Conversion (wt%) 78.2
Primary Reactor FTnIR Outlet [C2] (g/L) 21.4
Primary Reactor Viscosity (cP) 1,413
Secondary Reactor Control Temperature ( C) 190
Secondary Reactor Pressure (Psig) 730
Secondary Reactor Ethylene Conversion (wt%) 89.9
Secondary Reactor FTnIR Outlet [C2] (g/L) 7.8
Secondary Reactor Viscosity (cP) 711
Overall Ethylene conversion by vent (wt%) 93.8
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Table 3: Catalyst conditions used to make base resin.
CATALYST CE 1
Primary Reactor:
Catalyst Type CAT-A
Co-Catalyst-1 Molar Ratio 1.8
Co-Catalyst-1 Type RIBS-2
Co-Catalyst-2 Molar Ratio 4.9
Co-Catalyst-2 Type MMAO-3A
Secondary Reactor:
Catalyst Type CAT-A
Co-Catalyst-1 Molar Ratio 1.2
Co-Catalyst-1 Type RIBS-2
Co-Catalyst-2 Molar Ratio 5
Co-Catalyst-2 Type MMAO-3A
Table 4: Catalysts and catalyst components detailed nomenclature.
Description CAS Name
Zirconium, [2,2"-[1,3-propanediylbis(oxy-KO)]bis[3",5,5"-
tris(1,1-dimethylethyl)-5'-methyl[1,1':3',1"-terphenyl]-2'-olato-
CAT-A 1(0]]dimethyl-, (OC-6-33)-
Amines, bis(hydrogenated tallow alkyl)methyl,
RIBS-2 tetrakis(pentafluorophenyl)borate(1-)
Aluminoxanes, iso-Bu Me, branched, cyclic and linear; modified
MMAO-3A methyl aluminoxane
The base resin was modified as described below in order to produce the
Inventive
Examples.
Production of Inventive Example 1
The production was described previously for the base resin for Inventive
Example 1,
Comparative Example 1. This resin was compounded by co-feeding it through a
twin-screw
extruder with a masterbatch comprising 5 wt% of Irgafos 168 in 1.64 wt% of the
base resin
for Inventive Example 1. The thus modified resin was further compounded using
a
masterbatch comprising 2.0 wt% of the total resin; this masterbatch comprised
2,500 ppm of
CGX CR 946, an alkoxyamine derivative which is commercially available from
BASF, in a
low density polyethylene (LDPE) resin as the carrier (12 or MI of 2 and
density of 0.918
g/cc). The final amount of Irgafos 168 in the resin was 803 ppm and the final
amount of
CGX CR 946 in the resin was Si ppm. The amount of LDPE in the final resin was
2.0 wt%.
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Extrusion Conditions for Production of Inventive Example 1
The twin-screw extruder is a co-rotating, intermeshing, 40 mm twin screw
Century
ZSK-40 extruder equipped with a 150 Hp drive, 244 Armature amps (at maximum)
and
operating at 1200 screw rpm (at maximum). The length-to-diameter ratio is
37.13. The
screw is 1485 mm in length design comprising 24 conveying and 3 kneading
elements. There
is a nitrogen purge at the throat of the extruder and there are two feeders,
one feeding the
resin and the other the antioxidant-containing masterbatch. There are 9
barrels, the first three
having temperatures set to 25 C and the rest set to 220 C. The extruder
operates at 175 rpm.
A melt pump is attached to the twin-screw extruder on one end and to a single-
screw
extruder on the other. The melt pump is a Maag 100CC/revolution pump that
helps to
convey the molten polymer from the extruder and out of the remaining
downstream
equipment. It is powered by a 15 hp motor with a 20.55/1 reduction gear. The
pump is
equipped with a pressure transducer on the suction and discharge spool pieces,
and a 5,200
psi rupture disc on the outlet transition piece. There are heater zones on the
melt pump and
the inlet and outlet transition pieces, set to 220 C. The masterbatch
containing CGX CR 946
is injected to the resin using a Sterling 2 1/2 Inch single-screw extruder
equipped with a
rupture disc of 4,000 psig. The single-screw extruder operates at 50 rpm with
4 heated zone
temperatures set to 223 to 224 C.
Downstream of the melt pump is a static mixer, comprising 18 twisted-tape
Kenics
static mixer elements having 52 inches in total length. There are seven heater
zones on the
static mixer ranging from 218 to 234 C, depending on the time of the
experiment. The static
mixer is attached to an underwater Gala pelletizer equipped with a 12 hole
(2.36 mm hole
diameter) die. The cutter has a four-blade hub.
Inventive Ethylene-Based Polymer Compositions (Inventive Example 1):
Inventive ethylene-based polymer composition, i.e. Inventive Examples 1, was
prepared according to the above procedure. The process conditions used to
report the resin
used for modification into Inventive Example 1 are reported in Table 1-4.
Comparative Example 1 is an ethylene/1 -octene polyethylene produced as
described
under conditions reported in Tables 1-4 with an 12 of approximately 0.5 g/10
minutes and a
density of 0.935 g/cm3.
Characterization properties of the Inventive Example 1 and Comparative Example
1
are reported in Table 5-15.
The melt index, melt index ratio, and density are reported in Table 5.
Inventive
Example 1 has a lower melt index (12), and higher I10/12 than the comparative
example. The
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lower melt index is advantageous in terms of higher shrink properties as is
the higher 1102.
The density of all samples is relatively high as is desired for high modulus
shrink films.
DSC data are reported in Table 6. The melting temperatures, percent
crystallinities,
and crystallization temperatures for the Comparative Example are within the
range of these
properties shown for the Inventive Example.
DMS viscosity, tan delta, and complex modulus versus phase angle data are
given in
Tables 7 ¨ 9, respectively, and plotted in Figures 1 - 3, respectively. The
viscosity data of
Table 7 and Figure 1 as well as the viscosity at 0.1 rad/s over that at 100
rad/s in Table 7
show that the Inventive Example shows high shear thinning behavior of
viscosity decreasing
rapidly with increasing frequency as compared to the Comparative Example. From
Table 8
and Figure 2, the Inventive Example has low tan delta values or high
elasticity as compared
to the Comparative Example, especially at low frequencies such as 0.1 rad/s.
Table 9 and
Figure 3 show a form of the DMS data which is not influenced as greatly by the
overall melt
index (MI or 12) or molecular weight. The more elastic materials are lower on
this plot (i.e.,
lower phase angle for a given complex modulus); the Inventive Example is lower
on this plot
or more elastic than the Comparative Example.
Melt strength data is shown in Table 10 and plotted in Figure 4. The melt
strengths
are influenced by the melt index with the melt strength in general being
higher for lower melt
index materials. Additionally, more highly branched or modified materials are
expected to
have higher melt strengths. Inventive Example 1 has a high melt strength
value, relatively, as
compared to the Comparative Example.
GPC data for the Inventive Example and Comparative Example are shown in Table
11 and Figure 5. In general, the Inventive Example has a narrow Mw/Mn of less
than 4Ø
Zero shear viscosity (ZSV) data for the Inventive Example and Comparative
Example
are shown in Table 12. The Inventive Example has a high ZSV ratio (ZSVR) as
compared to
the Comparative Example.
Unsaturation data for the Inventive Example and Comparative Example are shown
in
Table 13. The Inventive Example has very low total unsaturation values.
Short chain branching distribution data are shown in Table 14 and Figure 6.
The
Inventive Example has a higher CDC. The Inventive Example has a monomodal or
bimodal
distribution excluding the soluble fraction at temperature ¨30 C.
The MW Ratio is measured by cross fractionation (TREF followed by GPC) for the
Inventive Example and Comparative Example. The MW Ratio is shown in Tables 15
and
Figure 7. The Inventive Example has a MW Ratio values increasing from a low
value (close
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to 0.24) with temperature, and reaching a maximum value of 1.00 at the highest
temperature.
The Inventive Example has a cumulative weight fraction less than 0.10 for the
temperature
fractions up to 50 C. At temperatures from 80 C to 100 C, the MW Ratio of the
Inventive
Example is higher than that of the Comparative Example.
Films
Monolayer films are made in a composition of 70 wt% linear low density
polyethylene (LLDPE) (IE 1 and CE 1 of Table 5) and 30 wt% LDPE in which the
LDPE
used is a high pressure low density polyethylene made by The Dow Chemical
Company
(LDPE 1321, 0.25 MI, 0.921 g/cm3).
Each formulation was compounded on a MAGUIRE gravimetric blender. A polymer
processing aid (PPA), DYNAMAR FX-5920A, was added to each formulation. The PPA
was added at 1 wt% of masterbatch, based on the total weight of the weight of
the
formulation. The PPA masterbatch (Ingenia AC-01-01, available from Ingenia
Polymers)
contained 8 wt% of DYNAMAR FX-5920A in a polyethylene carrier. This amounts to
800
ppm PPA in the polymer.
The monolayer blown films were made on an "8 inch die" with a polyethylene
"Davis
Standard Barrier II screw." External cooling by an air ring and internal
bubble cooling were
used. General blown film parameters, used to produce each blown film, are
shown in Table
16. The temperatures are the temperatures closest to the pellet hopper (Barrel
1), and in
increasing order, as the polymer was extruded through the die. The films were
run at 250
lb/hr. The films are tested for their various properties according to the test
methods described
below, and these properties are reported in Table 17.
Inventive Film 1 showed good MD and CD shrink tension and free shrink, which
is
advantageous for use in shrink film, comparable optics (haze, gloss, clarity),
and generally
good film properties (puncture and dart) when compared to the Comparative
Film.
Table 5: 12, 110/12, and Density
12 (g/10 min) 110/12 Density (g/cm3)
TEl 0.32 14.0 0.9331
CE1 0.51 11.3 0.9342
Table 6: DSC data
Tmi ( C) Heat of Fusion (J/g) % Cryst. Tel ( C)
TEl 125.1 175.5 60.1 113.4
CE1 125.0 176.4 60.4 111.5
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Table 7: DMS viscosity data
IE1 CE!
Frequency (rad/s) Viscosity (Pa-s) Viscosity (Pa-s)
0.1 42,579 29,502
0.16 35,912 25,698
0.25 29,782 21,954
0.40 24,383 18,530
0.63 19,823 15,482
1.00 16,029 12,891
1.58 12,984 10,746
2.51 10,476 8,923
3.98 8,470 7,414
6.31 6,848 6,162
10.00 5,536 5,106
15.85 4,436 4,213
25.12 3,570 3,432
39.81 2,856 2,792
63.10 2,268 2,249
100.00 1,790 1,797
Viscosity 0.1/100 23.8 16.4
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Table 8: DMS tan delta data
Frequency IE1 CE!
(rad/s) Tan Delta Tan Delta
0.1 1.49 1.86
0.16 1.38 1.69
0.25 1.29 1.57
0.40 1.23 1.49
0.63 1.18 1.43
1.00 1.15 1.40
1.58 1.14 1.37
2.51 1.13 1.36
3.98 1.12 1.34
6.31 1.11 1.31
10.00 1.10 1.28
15.85 1.08 1.23
25.12 1.05 1.18
39.81 1.01 1.12
63.10 0.97 1.06
100.00 0.92 0.99
Table 9: DMS G* and phase angle data
IE1 CE!
Phase
Frequency Angle Phase Angle
(rad/s) G* (Pa) (Degrees) G* (Pa) (Degrees)
0.1 4,258 56.21 2,950 61.75
0.16 5,692 54.02 4,073 59.38
0.25 7,481 52.23 5,515 57.56
0.40 9,707 50.79 7,377 56.14
0.63 12,507 49.77 9,768 55.09
1.00 16,029 49.09 12,891 54.40
1.58 20,579 48.67 17,032 53.93
2.51 26,314 48.42 22,414 53.59
3.98 33,719 48.25 29,515 53.22
6.31 43,210 48.04 38,880 52.72
10.00 55,360 47.69 51,061 51.98
15.85 70,308 47.12 66,777 50.99
25.12 89,664 46.34 86,216 49.74
39.81 114,000 45.34 111,000 48.25
63.10 143,000 44.13 142,000 46.55
100.00 179,000 42.60 180,000 44.62
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Table 10: Melt strength
Melt Strength (cN)
TEl 6.9
CE1 5.0
Table 11: GPC data by conventional GPC
Mw (g/mol) M. (g/mol) Mw/M. n (g/mol)
TEl 108,748 36,187 3.01 243,658
CE1 113,634 36,380 3.12 294,508
Table 12: Weight average molecular weight Mw from conventional GPC, Zero shear
viscosity ZSV, and ZSV Ratio.
Mw Log (Mw in Log (ZSV ZSV
(g/mol) ZSV (Pa-s) g/mol) in Pa-s) Ratio
IE 1 108,748 108,401 5.036 5.035 19.60
CE 1 113,634 49,300 5.056 4.693 7.59
Table 13: Unsaturations
Unsaturation Unit / 1,000,000 C
Total
Vinylene Trisubstituted Vinyl Vinylidene Unsaturations
IE 1 8 1 49 5 63
CE1 13 4 57 3 77
0
Table 14: CEF
Comonomer Comonomer Half Width Halfwidth StDev
CDC
Distribution Index Distribution Index ( C)
Stdev ( C)
TEl 0.784 5.912 2.856 0.483
162.2
CE1 0.796 3.634 2.710 0.746
106.7
Table 15: MW Ratio
Fraction 1 2 3 4 5 6 7 8 9 10 11 12
13 14 15 16
Temp , C 30 35 40 45 50 55 60 65 70 75 80
85 90 95 100 105
Wt%
(Temp) 0.9 0.1 0 0 0 0 0.2 0.3 0.4 0.7
1.1 2 3.9 47.1 42.8 0.6
Cumulative
IE1 weight
fraction
0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02 0.03 0.04 0.06 0.10
0.57 0.99 1.00
MW Ratio 0.24
0.21 0.22 0.71 1.00
Wt%
(Temp) 0.1 0 0 0 0 0 0 0 0.1 0.2 0.3
0.9 2.7 18.3 75.3 2.1
Cumulative
CE1 weight
fraction
0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.02 0.04
0.23 0.98 1.00
MW Ratio
0.09 0.44 0.61 1.00
,4z
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Table 16. Blown film process parameters used to produce films.
Blow up ratio (BUR) 2.5
Nominal Film thickness 2.0
Die gap (mil) 70
Air temperature ( F) 45
Temperature profile ( F)
Barrel 1 350
Barrel 2 425
Barrel 3 380
Barrel 4 325
Barrel 5 325
Screen Temperature 430
Adapter 430
Block 430
Lower Die 440
Inner Die 440
Upper Die 440
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Table 17: Blown Film properties
Example Comparative Film 1 Inventive Film 1
Film Thickness (mil) 1.86 1.96
Total Haze (%) 15.4 16.1
Internal Haze (%) 4.0 3.3
450 Gloss (%) 43.6 41.7
Clarity (%) 95.0 94.6
MD Shrink Tension (psi) 15.17 17.70
CD Shrink Tension (psi) 0.97 1.03
MD Free Shrinkage (%) 150 C 78.8 79.8
CD Free Shrinkage (%) 150 C 15.9 18.3
Puncture (ft-lbf/in3) 76 91
Dart Drop Impact A (g) 93 103
MD Tear (g) 72 75
CD Tear (g) 787 672
MD Tear (g/mil) Normalized 39 40
CD Tear (g/mil) Normalized 416 350
2% MD Secant Modulus (psi) 55,490 53,510
2% CD Secant Modulus (psi) 68,497 66,334
MD Break Stress (psi) 5,612 5,032
CD Break Stress (psi) 4,542 4,791
MD Strain at Break (%) 564 477
CD Strain at Break (%) 723 746
MD Stress at Yield (psi) 3,200 3,446
CD Stress at Yield (psi) 2,748 2,710
MD Strain at Yield (%) 96.1 101.5
CD Strain at Yield (%) 9.7 9.4
Test Methods
Test methods include the following:
Melt Index
Melt index, or 12 or MI, is measured in accordance with ASTM D 1238-10,
Condition
190 C/2.16 kg, and is reported in grams eluted per 10 minutes. The 110 is
measured in accordance
with ASTM D 1238, Condition 190 C/10 kg, and is reported in grams eluted per
10 minutes.
Density
Samples for density measurements are prepared according to ASTM D 4703-10.
Samples are
pressed at 374 F (190 C) for five minutes at 10,000 psi (68 MPa). The
temperature is maintained at
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374 F (190 C) for the above five minutes, and then the pressure is increased
to 30,000 psi (207
MPa) for three minutes. This is followed by a one minute hold at 70 F (21 C)
and 30,000 psi (207
MPa). Measurements are made within one hour of sample pressing using ASTM D792-
08, Method
B.
DSC Crystallinity
Differential Scanning Calorimetry (DSC) can be used to measure the melting and
crystallization behavior of a polymer over a wide range of temperature. For
example, the TA
Instruments Q1000 DSC, equipped with an RCS (refrigerated cooling system) and
an autosampler is
used to perform this analysis. During testing, a nitrogen purge gas flow of 50
ml/min is used. Each
sample is melt pressed into a thin film at about 175 C; the melted sample is
then air-cooled to room
temperature (-25 C). A 3-10 mg, 6 mm diameter specimen is extracted from the
cooled polymer,
weighed, placed in a light aluminum pan (ca 50 mg), and crimped shut. Analysis
is then performed
to determine its thermal properties.
The thermal behavior of the sample is determined by ramping the sample
temperature up and
down to create a heat flow versus temperature profile. First, the sample is
rapidly heated to 180 C
and held isothermal for 3 minutes in order to remove its thermal history.
Next, the sample is cooled
to -40 C at a 10 C/minute cooling rate and held isothermal at -40 C for 3
minutes. The sample is
then heated to 150 C (this is the "second heat" ramp) at a 10 C/minute
heating rate. The cooling
and second heating curves are recorded. The cool curve is analyzed by setting
baseline endpoints
from the beginning of crystallization to -20 C. The heat curve is analyzed by
setting baseline
endpoints from -20 C to the end of melt. The values determined are peak
melting temperature (Tm),
peak crystallization temperature (T,), heat of fusion (Hf) (in Joules per
gram), and the calculated %
crystallinity for polyethylene samples using Equation 1, shown below:
% Crystallinity = ((Hf)/(292 J/g)) x 100
Equation 1
The heat of fusion (Hf) and the peak melting temperature are reported from the
second heat
curve. Peak crystallization temperature is determined from the cooling curve.
Dynamic Mechanical Spectroscopy (DMS) Frequency Sweep
Melt rheology, a constant temperature frequency sweep, was performed using a
TA
Instruments Advanced Rheometric Expansion System (ARES) rheometer equipped
with 25 mm
parallel plates under a nitrogen purge. Frequency sweeps were performed at 190
C for all samples
at a gap of 2.0 mm and at a constant strain of 10%. The frequency interval was
from 0.1 to 100
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radians/second. The stress response was analyzed in terms of amplitude and
phase, from which the
storage modulus (G'), loss modulus (G"), and dynamic melt viscosity (ri*) were
calculated. The
methods described in van Gurp and Palmen, Rheology Bulletin (1998) 67:5-8;
Trinkle, S. and C.
Friedrich, Rheologica Acta, 2001. 40(4); p. 322-328, were used to prepare the
data presented in Fig.
3 (Van-Gurp Palmen plot).
CEF Method
Comonomer distribution analysis is performed with Crystallization Elution
Fractionation
(CEF) (PolymerChar in Spain) (B. Monrabal et al, Macromol. Symp. 257, 71-79
(2007)). Ortho-
dichlorobenzene (ODCB) with 300ppm antioxidant butylated hydroxytoluene (BHT)
is used as the
solvent. Sample preparation is done with autosampler at 160 C for 2 hours
under shaking at 4
mg/ml (unless otherwise specified). The injection volume is 300 ill. The
temperature profile of the
CEF is: crystallization at 3 C/min from 110 C to 30 C, thermal equilibrium at
30 C for 5 minutes,
soluble fraction (SF) time at 2minutes, elution at 3 C/min from 30 C to 140 C.
The flow rate during
crystallization is at 0.052 ml/min. The flow rate during elution is at 0.50
ml/min. The data is
collected at one data point/second.
The CEF column is packed by the Dow Chemical Company with glass beads at 125
um 6%
(MO-SCI Specialty Products) with 1/8 inch stainless tubing. Glass beads are
acid washed by MO-
SCI Specialty with the request from the Dow Chemical Company. Column volume is
2.06 ml.
Column temperature calibration is performed by using a mixture of NIST
Standard Reference
Material Linear polyethylene 1475a (1.0mg/m1) and Eicosane (2mg/m1) in ODCB.
The temperature
is calibrated by adjusting the elution heating rate so that NIST linear
polyethylene 1475a has a peak
temperature at 101.0 C, and Eicosane has a peak temperature of 30.0 C. The CEF
column resolution
is calculated with a mixture of NIST linear polyethylene 1475a (1.0mg/m1) and
hexacontane (Fluka,
purum, >97.0%, lmg/m1). A baseline separation of hexacontane and NIST
polyethylene 1475a is
achieved. The area of hexacontane (from 35.0 to 67.0 C) to the area of NIST
1475a from 67.0 to
110.0 C is 50 to 50, the amount of soluble fraction below 35.0 C is <1.8 wt%.
The CEF column
resolution is defined in Equation 2, as below, where the column resolution is
6.0:
Peak temperature of NIST 1475a - Peak Temperature of Hexacontane
Resolution =
Half - height Width of NIST 1475a + Half - height Width of Hexacontane
Equation 2
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CDC Method
Comonomer distribution constant (CDC) is calculated from comonomer
distribution profile
by CEF. CDC is defined as Comonomer Distribution Index divided by Comonomer
Distribution
Shape Factor multiplying by 100 as shown in Equation 3, shown below:
CDC
Comonomer Distribution Index Comonomer Distribution Index *100
=
Comonomer Distribution Shape Factor Half Width/Stdev
Equation 3
Comonomer distribution index stands for the total weight fraction of polymer
chains with the
comonomer content ranging from 0.5 of median comonomer content (Cmem.) and 1.5
of Cmethan from
35.0 to 119.0 C. Comonomer Distribution Shape Factor is defined as a ratio of
the half width of
comonomer distribution profile divided by the standard deviation of comonomer
distribution profile
from the peak temperature (Tp).
CDC is calculated from comonomer distribution profile by CEF, and CDC is
defined as
Comonomer Distribution Index divided by Comonomer Distribution Shape Factor
multiplying by
100 as shown in Equation 3 and wherein Comonomer Distribution Index stands for
the total weight
fraction of polymer chains with the comonomer content ranging from 0.5 of
median comonomer
content (Cmethan) and 1.5 of Cmethan from 35.0 to 119.0 C, and wherein
Comonomer Distribution
Shape Factor is defined as a ratio of the half width of comonomer distribution
profile divided by the
standard deviation of comonomer distribution profile from the peak temperature
(Tp).
CDC is calculated according to the following steps:
(A) Obtain a weight fraction at each temperature (I) (wT(T)) from 35.0 C to
119.0 C with a
temperature step increase of 0.200 C from CEF according to Equation 4, as
shown below;
119.0
f WT ( T )dT =1
Equation 4
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(B) Calculate the median temperature (T niedzan, 1 at cumulative weight
fraction of 0.500,
according to Equation 5, as shown below;
T medzan
wT (T)dT = 0.5
Equation 5
(C) Calculate the corresponding median comonomer content in mole % (Cmedian)
at the
median temperature (T medzani 1 by using comonomer content calibration curve
according to Equation 6,
as shown below;
ln(1 ¨ comonomerc ontent) = 207.26 + 0.5533
273.12 + T
R2 = 0.997
Equation 6
(D) Construct a comonomer content calibration curve by using a series of
reference
materials with known amount of comonomer content, i.e., eleven reference
materials with narrow
comonomer distribution (mono-modal comonomer distribution in CEF from 35.0 to
119.0 C) with
weight average Mw of 35,000 to 115,000 (measured via conventional GPC) at a
comonomer content
ranging from 0.0 mole% to 7.0 mole% are analyzed with CEF at the same
experimental conditions
specified in CEF experimental sections;
(E) Calculate comonomer content calibration by using the peak temperature (Tv)
of each
reference material and its comonomer content; The calibration is calculated
from each reference
material as shown in Equation 6, wherein: R2 is the correlation constant;
(F) Calculate Comonomer Distribution Index from the total weight fraction with
a
comonomer content ranging from 0.5 *Cmedian to 1.5* Cmedian, and if Tmedian is
higher than 98.0 C,
Comonomer Distribution Index is defined as 0.95;
(G) Obtain Maximum peak height from CEF comonomer distribution profile by
searching
each data point for the highest peak from 35.0 C to 119.0 C (if the two peaks
are identical, then the
lower temperature peak is selected); half width is defined as the temperature
difference between the
front temperature and the rear temperature at the half of the maximum peak
height, the front
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temperature at the half of the maximum peak is searched forward from 35.0 C,
while the rear
temperature at the half of the maximum peak is searched backward from 119.0 C,
in the case of a
well defined bimodal distribution where the difference in the peak
temperatures is equal to or greater
than the 1.1 times of the sum of half width of each peak, the half width of
the inventive ethylene-
based polymer composition is calculated as the arithmetic average of the half
width of each peak;
(H) Calculate the standard deviation of temperature (Stdev) according to
Equation 7, as shown
below:
1190 __________________
Stdev = E (T ¨ T p)2 * WT ( T)
35.0
Equation 7
Conventional GPC /V1,4,_gp, determination
To obtain Mw-gpc values, the chromatographic system consist of either a
Polymer
Laboratories Model PL-210 or a Polymer Laboratories Model PL-220 equipped with
a refractive
index (RI) concentration detector. The column and carousel compartments are
operated at 140 C.
Three Polymer Laboratories 10-pm Mixed-B columns are used with a solvent of
1,2,4-
trichlorobenzene. The samples are prepared at a concentration of 0.1 g of
polymer in 50 mL of
solvent. The solvent used to prepare the samples contain 200 ppm of the
antioxidant butylated
hydroxytoluene (BHT). Samples are prepared by agitating lightly for 4 hours at
160 C. The
injection volume used is 100 microliters and the flow rate is 1.0 mL/min.
Calibration of the GPC
column set is performed with twenty one narrow molecular weight distribution
polystyrene standards
purchased from Polymer Laboratories. The polystyrene standard peak molecular
weights are
converted to polyethylene molecular weights shown in the Equation 8, as shown
below where M is
the molecular weight, A has a value of 0.4316 and B is equal to 1.0:
Mpolyethylene¨A(MpolystyrendB
Equation 8.
A third order polynomial is determined to build the logarithmic molecular
weight calibration
as a function of elution volume. The weight-average molecular weight by the
above conventional
calibration is defined as Mwõ in Equation 9 as shown below:
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Mw (cc) = ERI1*mee,1
Equation 9
where, the summation is across the GPC elution curve, with RI and Mõ
represents the RI detector
signal and conventional calibration molecular weight at each GPC elution
slice. Polyethylene
equivalent molecular weight calculations are performed using PolymerChar Data
Processing
Software (GPC One). The precision of the weight-average molecular weight AMw
is excellent at
< 2.6 %.
Creep zero shear viscosity measurement method:
Zero-shear viscosities are obtained via creep tests that were conducted on an
AR-G2 stress
controlled rheometer (TA Instruments; New Castle, Del) using 25-mm-diameter
parallel plates at
190 C. The rheometer oven is set to test temperature for at least 30 minutes
prior to zeroing fixtures.
At the testing temperature a compression molded sample disk is inserted
between the plates and
allowed to come to equilibrium for 5 minutes. The upper plate is then lowered
down to 50 jim
above the desired testing gap (1.5 mm). Any superfluous material is trimmed
off and the upper plate
is lowered to the desired gap. Measurements are done under nitrogen purging at
a flow rate of 5
L/min. Default creep time is set for 2 hours.
A constant low shear stress of 20 Pa is applied for all of the samples to
ensure that the steady
state shear rate is low enough to be in the Newtonian region. The resulting
steady state shear rates
are in the range of 10-3 to 10-4 s-1 for the samples in this study. Steady
state is determined by taking
a linear regression for all the data in the last 10% time window of the plot
of log (J(t)) vs. log(t),
where J(t) is creep compliance and t is creep time. If the slope of the linear
regression is greater than
0.97, steady state is considered to be reached, then the creep test is
stopped. The steady state shear
rate is determined from the slope of the linear regression of all of the data
points in the last 10% time
window of the plot of 8 VS. t, where 8 is strain. The zero-shear viscosity is
determined from the ratio
of the applied stress to the steady state shear rate.
In order to determine if the sample is degraded during the creep test, a small
amplitude
oscillatory shear test is conducted before and after the creep test on the
same specimen from 0.1 to
100 rad/s. The complex viscosity values of the two tests are compared. If the
difference of the
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viscosity values at 0.1 rad/s is greater than 5%, the sample is considered to
have degraded during the
creep test, and the result is discarded.
If the viscosity difference is greater than 5%, a fresh or new sample (i.e.,
one that a viscosity
test has not already been run on) is stabilized and the testing on this new
stabilized sample is then
run by the Creep Zero Shear Viscosity Method. This was done for IEl. The
stabilization method is
described herein. The desired amount of pellets to stabilize are weighed out
and reserved for later
use. The ppm of antioxidants are weighed out in a flat bottom flask with a
screen lid or secured
screen cover. The amount of antioxidants used are 1500 ppm Irganox 1010 and
3000 ppm Irgafos
168. Add enough acetone to the flask to generously cover the additives,
approximately 20m1. Leave
the flask open. Heat the mixture on a hotplate until the additives have
dissolved, swirling the
mixture occasionally. The acetone will heat up quickly and the swirling will
help it to dissolve. Do
not attempt to bring it to a boil. Turn the hot plate off and move the flask
to the other end of the
hood. Gently add the pellets to the flask. Swirl the hot solution so as to wet
all sides of the pellets.
Slowly add more acetone. Generously cover the pellets with extra acetone but
leave a generous
amount of head space so that when the flask is put in the vacuum oven the
solution will not come out
of the flask. Cover the flask with a screen allowing it to vent while ensuring
the pellets/solution will
not come out. Place the flask in a pan, in a 50 C vacuum oven. Close the oven
and crack the
nitrogen open slowly. After 30 minutes to 2 hours (30 minutes is sufficient
for very small amounts
e.g. 10g of pellets), very slowly apply the vacuum and adjust the nitrogen
flow so that you have a
light sweep. Leave under 50 C vacuum with N2 sweep for approximately 14 hours.
Remove from
oven. The pellets may be easier to remove from the flask while still warm.
Rewet pellets with a
small amount of acetone only if necessary for removal.
Zero-shear viscosity ratio (ZSVR) is defined as the ratio of the zero-shear
viscosity (ZSV) of the
branched polyethylene material to the ZSV of the linear polyethylene material
at the equivalent
weight average molecular weight (Mw-gpc) as shown in the Equation 10, as
below:
ERII *Mee,
Mw (cc) = 1v,
LaIRI1
Equation 10.
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The ZSV value is obtained from creep test at 190 C via the method described
above. The
Mw-gpc value is determined by the conventional GPC method as described above.
The correlation
between ZSV of linear polyethylene and its Mw-gpc was established based on a
series of linear
polyethylene reference materials. A description for the ZSV-Mw relationship
can be found in the
ANTEC proceeding: Karjala, Teresa P.; Sammler, Robert L.; Mangnus, Marc A.;
Hazlitt, Lonnie G.;
Johnson, Mark S.; Hagen, Charles M., Jr.; Huang, Joe W. L.; Reichek, Kenneth
N. Detection of
low levels of long-chain branching in polyolefins. Annual Technical Conference
- Society of
Plastics Engineers (2008), 66th 887-891.
Melt strength
Melt strength is measured at 190 C using a Goettfert Rheotens 71.97
(Goettfert Inc.; Rock
Hill, SC), melt fed with a Goettfert Rheotester 2000 capillary rheometer
equipped with a flat
entrance angle (180 degrees) of length of 30 mm and diameter of 2 mm. The
pellets are fed into the
barrel (L=300 mm, Diameter=12 mm), compressed and allowed to melt for 10
minutes before being
extruded at a constant piston speed of 0.265 mm/s, which corresponds to a wall
shear rate of 38.2s-1
at the given die diameter. The extrudate passes through the wheels of the
Rheotens located at
100 mm below the die exit and is pulled by the wheels downward at an
acceleration rate of
2.4 mm/s2. The force (in cN) exerted on the wheels is recorded as a function
of the velocity of the
wheels (in mm/s). Melt strength is reported as the plateau force (cN) before
the strand broke.
TREF column
The TREF columns are constructed from acetone-washed 1/8inch x 0.085inch 316
stainless
steel tubing. The tubing is cut to a length of 42 inches and packed with a dry
mixture (60:40
volume: volume) of pacified 316 stainless steel cut wire of 0.028 inch
diameter (Pellet Inc., North
Tonawanda, NY) and 30-40 mesh spherical technical grade glass beads. This
combination of column
length and packing material results in an interstitial volume of approximately
1.75 mL. The TREF
column ends are capped with Valco microbore HPLC column end fittings equipped
with a 10 gm
stainless steel screen. These column ends provide the TREF columns with a
direct connection to the
plumbing of the cross fractionation instrument within the TREF oven. The TREF
columns are
coiled, outfitted with an resistance temperature detector (RTD) temperature
sensor, and wrapped
with glass insulation tape before installation. During installation, extra
care is given to level
placement of the TREF column with the oven to ensure adequate thermal
uniformity within the
column. Chilled air is provided at 40 L/min to the TREF ovens via a chiller
whose bath temperature
is 2 C.
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TREF column temperature calibration
The reported elution temperatures from the TREF column are adjusted with the
heating rate
used in the temperature range of 110 C to 30 C such that the observed
compositions versus elution
temperatures agree with those previously reported (L. Wild, R.T. Ryle et al.,
J. Polymer Science
Polymer Physics Edition 20, 441-455(1982)).
Sample Preparation
The sample solutions are prepared as 4 mg/mL solutions in 1,2,4-
trichlorobenzene (TCB)
containing 180ppm butylated hydroxytoluene (BHT) and the solvent is sparged
with nitrogen. A
small amount of decane is added as a flow rate marker to the sample solution
for GPC elution
validation. Dissolution of the samples is completed by gentle stirring at 145
C for four hours.
Sample Loading
Samples are injected via a heated transfer line to a fixed loop injector
(Injection loop of
5004) directly onto the TREF column at 145 C.
Temperature profile of TREF column
After the sample has been injected onto the TREF column, the column is taken
"off-line" and
allowed to cool. The temperature profile of the TREF column is as follows:
cooling down from
145 C to 110 C at 1.2 C/min, cooling down from 110 C to 30 C at 0.133 C/min,
and thermal
equilibrium at 30 C for 30 minutes. During elution, the column is placed back
"on-line" to the flow
path with a pump elution rate of 0.9 ml/min for 1.0 minute. The heating rate
of elution is
0.099 C/min from 30 C to 105 C.
Elution from TREF column
The 16 fractions are collected from 30 C to 110 C at 5 C increments per
fraction. Each
fraction is injected for GPC analysis. Each of the 16 fractions are injected
directly from the TREF
column over a period of 1.0 minute onto the GPC column set. The eluent is
equilibrated at the same
temperature as the TREF column during elution by using a temperature pre-
equilibration coil
(Gillespie and Li Pi Shan et al., Apparatus for Method for Polymer
Characterization,
W02006081116). Elution of the TREF is performed by flushing the TREF column at
0.9 ml/min for
1.0 min. The first fraction, Fraction (30 C), represents the amount of
material remaining soluble in
TCB at 30 C. Fraction (35 C), Fraction (40 C), Fraction (45 C), Fraction (50
C), Fraction (55 C),
Fraction (60 C), Fraction (65 C), Fraction (70 C), Fraction (75 C), Fraction
(80 C), Fraction (85 C),
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Fraction (90 C), Fraction (95 C), Fraction (100 C), and Fraction (105 C)
represent the amount of
material eluting from the TREF column with a temperature range of 30.01 to 35
C, 35.01 to 40 C,
40.01 to 45 C, 45.01 to 50 C, 50.01 to 55 C, 55.01 to 60 C, 60.01 to 65 C,
65.01 to 70 C, 70.01 to
75 C, 75.01 to 80 C, 80.01 to 85 C, 85.01 to 90 C, 90.01 to 95 C, 95.01 to 100
C, and 100.01 to
105 C, respectively.
GPC Parameters
The cross fractionation instrument is equipped with one 10 gm guard column and
four Mixed
B-LS 10 gm columns (Varian Inc., previously PolymerLabs), and the IR-4
detector from
PolymerChar (Spain) is the concentration detector. The GPC column set is
calibrated by running
twenty one narrow molecular weight distribution polystyrene standards. The
molecular weight
(MW) of the standards ranges from 580 to 8,400,000 g/mol, and the standards
are contained in 6
"cocktail" mixtures. Each standard mixture ("cocktail") has at least a decade
of separation between
individual molecular weights. The standards are purchased from Polymer
Laboratories (Shropshire,
UK). The polystyrene standards are prepared at 0.025 g in 50 mL of solvent for
molecular weights
equal to or greater than 1,000,000 g/mol and 0.05 g in 50 mL of solvent for
molecular weights less
than 1,000,000 g/mol. The polystyrene standards are dissolved at 145 C with
gentle agitation for 30
minutes. The narrow standards mixtures are run first and in the order of
decreasing highest
molecular weight component to minimize degradation. A logarithmic molecular
weight calibration is
generated using a first-order polynomial fit as a function of elution volume.
The polystyrene
standard peak molecular weights are converted to polyethylene molecular
weights using Equation 8
as described in Williams and Ward, J. Polym. Sci., Polym. Let., 6, 621 (1968)
where M is the
molecular weight, A has a value of 0.40 and B is equal to 1Ø
The plate count for the four Mixed B-LS 10 gm columns needs to be at least
19,000 by using
a 500 ill injection volume of a drop of a 50:50 mixture of decane and 1,2,4-
trichlorobenzene (TCB)
in 25 mL of TCB bypassing the TREF column. The plate count calculates from the
peak retention
volume (RVpk max) and the retention volume (RV) width at 1/2 height (50% of
the chromatographic
peak) to obtain an effective measure of the number of theoretical plates in
the column by using
Equation 11 as shown below and as set forth in Striegel and Yau et al.,
"Modern Size-Exclusion
Liquid Chromatography", Wiley, 2009, Page 86:
Plate Count = 5.54 * [RVpk max / (RN/Rear 50% pk ht - RVFront 50% pk ht)]2
Equation 11
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MWD Analysis for Each Fraction
The molecular weight distribution (MWD) of each fraction is calculated from
the integrated
GPC chromatogram to obtain the weight average molecular weight for each
fraction,
MW(Temperature).
The establishment of the upper integration limit (high molecular weight end)
is based on the
visible difference between the peak rise from the baseline. The establishment
of the lower
integration limit (low molecular weight end) is viewed as the return to the
baseline.
The area of each individual GPC chromatogram corresponds to the amount of
polyolefinic
material eluted from the TREF fraction. The weight percentage of the TREF
fraction at a specified
temperature range of the Fraction, Wt%(Temperature), is calculated as the area
of the individual
GPC chromatogram divided by the sum of the areas of the 16 individual GPC
chromatograms. The
GPC molecular weight distribution calculations (Mn, Mw, and Mz) are performed
on each
chromatogram and reported only if the weight percentage of the TREF fraction
is larger than
1.0wt%. The GPC weight-average molecular weight, Mw, is reported as MW
(Temperature) of each
chromatogram.
Wt% (30 C) represents the amount of material eluting from the TREF column at
30 C during
the TREF elution process. Wt% (35 C), Wt% (40 C), Wt% (45 C), Wt% (50 C), Wt%
(55 C), Wt%
(60 C), Wt% (65 C), Wt% (70 C), Wt% (75 C), Wt% (80 C), Wt% (85 C), Wt% (90
C), Wt%
(95 C), Wt% (100 C), and Wt% (105 C) represent the amount of material eluting
from the TREF
column with a temperature range of 30.01 C to 35 C, 35.01 C to 40 C, 40.01 to
45 C, 45.01 C to
50 C, 50.01 C to 55 C, 55.01 C to 60 C, 60.01 C to 65 C, 65.01 C to 70 C,
70.01 C to 75 C,
75.01 C to 80 C, 80.01 C to 85 C, 85.01 C to 90 C, 90.01 C to 95 C, 95.01 C to
100 C, and
100.01 C to 105 C, respectively. The cumulative weight fraction is defined as
the sum of the Wt %
of the fractions up to a specified temperature. The cumulative weight fraction
is 1.00 for the whole
temperature range.
The highest temperature fraction molecular weight, MW (Highest Temperature
Fraction), is
defined as the molecular weight calculated at the highest temperature
containing more than 1.0 wt%
material. The MW Ratio of each temperature is defined as the MW (Temperature)
divided by MW
(Highest Temperature Fraction).
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11-I NMR method
3.26 g of stock solution is added to 0.133 g of polyolefin sample in 10 mm NMR
tube. The
stock solution is a mixture of tetrachloroethane-d2 (TCE) and
perchloroethylene (50:50, w:w) with
0.001M Cr3+. The solution in the tube is purged with N2 for 5 minutes to
reduce the amount of
oxygen. The capped sample tube is left at room temperature overnight to swell
the polymer sample.
The sample is dissolved at 110 C with shaking. The samples are free of the
additives that may
contribute to unsaturation, e.g. slip agents such as erucamide.
The 1H NMR are run with a 10 mm cryoprobe at 120 C on Bruker AVANCE 400 MHz
spectrometer.
Two experiments are run to get the unsaturation: the control and the double
presaturation
experiments.
For the control experiment, the data is processed with exponential window
function with
LB=1 Hz, baseline was corrected from 7 to -2 ppm. The signal from residual 1H
of TCE is set to
100, the integral 'total from -0.5 to 3 ppm is used as the signal from whole
polymer in the control
experiment. The number of CH2 group, NCH2, in the polymer is calculated as
following:
NCH2=It /2
otal _
For the double presaturation experiment, the data is processed with
exponential window
function with LB=1 Hz, baseline was corrected from 6.6 to 4.5 ppm. The signal
from residual 1H of
TCE is set to 100, the corresponding integrals for unsaturations (Ivinylene,
Itrisubstituted, 'vinyl and Ivinylidene)
were integrated. The number of unsaturation units for vinylene,
trisubstituted, vinyl and vinylidene
are calculated:
Nvinylene = Ivinylene/2
Ntrisubstituted = Itrisubstituted
Nvinyl = IvinyV2
Nvinylidene = Ivinylidene/2
The unsaturation unit/ 1,000,000 carbons is calculated as following:
Nvinylene/ 1 5000 5 000C = (Nvinylene/NCH2)*1,000,000
Ntrisubstituted/1,000,000C = (Ntrisubstituted/NCH2)* 1,000,000
Nvinyl/ 1 5000 5 000C = (Nvinyl/NCH2)*1,000,000
Nvinylidene/ 1,000 5 0 0 0 C = (Nvinylidene/NCH2)* 1,000,000
The requirement for unsaturation NMR analysis includes: level of quantitation
is 0.47
0.02/1,000,000 carbons for Vd2 with 200 scans (less than 1 hour data
acquisition including time to
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run the control experiment) with 3.9 wt% of sample (for Vd2 structure, see
Macromolecules, vol. 38,
6988, 2005), 10 mm high temperature cryoprobe. The level of quantitation is
defined as signal to
noise ratio of 10.
The chemical shift reference is set at 6.0 ppm for the 1H signal from residual
proton from
TCT-d2. The control is run with ZG pulse, TD 32768, NS 4, DS 12, SWH 10,000
Hz, AQ 1.64s, D1
14s. The double presaturation experiment is run with a modified pulse
sequence, 01P 1.354 ppm,
02P 0.960 ppm, PL9 57db, PL21 70 db, TD 32768, NS 200, DS 4, SWH 10,000 Hz, AQ
1.64s, D1 1
s, D13 13s.
Extensional Viscosity
Extensional viscosity was measured by an extensional viscosity fixture (EVF)
of TA
Instruments (New Castle, DE), attached onto a model ARES rheometer of TA
Instruments.
Extensional viscosity at 150 C, and at Hencky strain rates of 10 s-1, 1 s-1
and 0.1 s-1, was measured.
A sample plaque was prepared on a programmable Tetrahedron model MTP8 bench
top press. The
program held 3.8 grams of the melt at 180 C, for five minutes, at a pressure
of 1 x 107 Pa, to make a
"75 mm x 50 mm" plaque with a thickness from 0.7 mm to 1.1 mm. The TEFLON
coated chase
containing the plaque was then removed to the bench top to cool. Test
specimens were then die-cut
from the plaque using a punch press and a handheld die with the dimensions of
"10x18 mm
(WidthxLength)." The specimen thickness was in the range of about 0.7 mm to
about 1.1 mm.
The rheometer oven that encloses the EVF fixture was set to a test temperature
of 150 C, and
the test fixtures that contact the sample plaque were equilibrated at this
temperature for at least 60
minutes. The test fixtures were then "zeroed" by using the test software, to
cause the fixtures to
move into contact with each other. Then the test fixtures were moved apart to
a set gap of 0.5 mm.
The width and the thickness of each plaque were measured at three different
locations on the plaque
with a micrometer, and the average values of the thickness and width were
entered into the test
software (TA Orchestrator version 7.2). The measured density of the sample at
room temperature
was entered into the test software. For each sample, a value of "0.782 g/cc"
was entered for the
density at 150 C. These values are entered into the test software to allow
calculation of the actual
dimensions of the plaque at the test temperature. The sample plaque was
attached, using a pin, onto
each of the two drums of the fixture. The oven was then closed, and the
temperature was allowed to
equilibrate to 150 C 0.5 C. As soon as the temperature entered this range, a
stopwatch was
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manually started, and after 60 seconds, the automated test was started by
clicking the software
"Begin Test" button.
The test was divided into three automated steps. The first step was a "pre-
stretch step" that
stretched the plaque at a very low strain rate of 0.005 s-1 for 11 seconds.
The purpose of this step
was to reduce plaque buckling, introduced when the plaque was loaded, and to
compensate for the
thermal expansion of the sample, when it was heated above room temperature.
This step was
followed by a "relaxation step" of 60 seconds, to minimize the stress
introduced in the pre-stretch
step. The third step was the "measurement step," where the plaque was
stretched at the pre-set
Hencky strain rate. The data collected in the third step was stored, and then
exported to Microsoft
Excel, where the raw data was processed into the Strain Hardening Factor (SHF)
values reported
herein.
Shear Viscosity for strain hardening
Sample preparation for shear viscosity measurement
Specimens for shear viscosity measurements were prepared on a programmable
Tetrahedron
model MTP8 bench top press. The program held 2.5 grams of the melt at 180 C,
for five minutes, in
a cylindrical mold, at a pressure of 1 x 107 Pa, to make a cylindrical part
with a diameter of 30 mm
and a thickness of 3.5 mm. The chase was then removed to the bench top to cool
down to room
temperature. Round test specimens were then die-cut from the plaque using a
punch press and a
handheld die with a diameter of 25 mm. The specimen was about 3.5 mm thick.
Shear viscosity measurement
Shear viscosity (Eta*) was obtained from a steady shear start-up measurement
that was
performed with the model ARES rheometer of TA Instruments, at 150 C, using "25
mm parallel
plates" at a gap of 2.0 mm, and under a nitrogen purge. In the steady shear
start-up measurement, a
constant shear rate of 0.005 s1 was applied to the sample for 100 seconds.
Shear viscosities were
collected as a function of time in the logarithmic scale. A total of 200 data
points were collected
within the measurement period. The Strain Hardening Factor (SHF) is the ratio
of the extensional
viscosity to three times of the shear viscosity, at the same measurement time
and at the same
temperature.
Additives Determination
Additive levels, such as the Irgafos 168 level, may be determined as in:
Standard Test Method for Determination of Antioxidants and Erucamide Slip
Additives in
Polyethylene Using Liquid Chromatography (LC); ASTM D6953-11, ASTM
International: 2011.
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Standard Practice for Extraction of Additives in Polyolefin Plastics; ASTM
D7210-13; ASTM
International: 2013.
Film Testing Conditions
The following physical properties are measured on the films produced:
= Total (Overall), Surface and Internal Haze: Samples measured for internal
haze and overall
haze are sampled and prepared according to ASTM D 1003. Internal haze was
obtained via
refractive index matching using mineral oil on both sides of the films. A
Hazeguard Plus
(BYK-Gardner USA; Columbia, MD) is used for testing. Surface haze is
determined as the
difference between overall haze and internal haze.
= 45 Gloss: ASTM D-2457.
= MD and CD Elmendorf Tear Strength: ASTM D-1922.
= MD and CD Tensile Strength: ASTM D-882.
= Dart Impact Strength: ASTM D-1709.
= Puncture: Puncture is measured on an Instron Model 4201 with Sintech
Testworks Software
Version 3.10. The specimen size is 6 inch x 6 inch and 4 measurements are made
to
determine an average puncture value. The film is conditioned for 40 hours
after film
production and at least 24 hours in an ASTM controlled laboratory. A 100 lb
load cell is
used with a round specimen holder. The specimen is a 4 inch circular specimen.
The
puncture probe is a 1/2 inch diameter polished stainless steel ball (on a 0.25
inch rod) with a
7.5 inch maximum travel length. There is no gauge length; the probe is as
close as possible
to, but not touching, the specimen. The crosshead speed used is 10
inches/minute. The
thickness is measured in the middle of the specimen. The thickness of the
film, the distance
the crosshead traveled, and the peak load are used to determine the puncture
by the software.
The puncture probe is cleaned using a "Kim-wipe" after each specimen.
= Shrink tension is measured according to the method described in Y. Jin,
T. Hermel-
Davidock, T. Karjala, M. Demirors, J. Wang, E. Leyva, and D. Allen, "Shrink
Force
Measurement of Low Shrink Force Films", SPE ANTEC Proceedings, p. 1264 (2008).
= % Free Shrink: A single layer square film with a dimension of 10.16 cm x
10.16 cm is cut
out by a punch press from a film sample along the edges of the machine
direction (MD) and
the cross direction (CD). The film is then placed in a film holder and the
film holder is
immersed in a hot-oil bath at 150 C for 30 seconds. The holder is then
removed from the oil
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CA 02955941 2017-01-20
WO 2016/014281 PCT/US2015/040290
bath. After oil is drained out, the length of film is measured at multiple
locations in each
direction and the average is taken as the final length. The % free shrink is
determined from
Equation 12 as below:
Initial Length) ¨ (Final Length) x 100
Initial Length
Equation 12.
The present invention may be embodied in other forms without departing from
the spirit and
the essential attributes thereof, and, accordingly, reference should be made
to the appended claims,
rather than to the foregoing specification, as indicating the scope of the
invention.
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